JP2000079754A - Recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To erase one portion alone by carrying an ink jet printing pattern with a pigment ink without a compatibility, on the surface of an ink accepting layer carrying an ink jet printing pattern with a dye ink, which is provided at least on one surface of a base material film. SOLUTION: On one surface of a base material film 1, an ink accepting layer 2 comprising a specified composition is provided, and an ink jet printing pattern 3 with a dye ink is formed under a state being infiltrated to the ink accepting layer 2, and in addition, an ink jet printing pattern 4 with a pigment ink is carried on the surface of the ink accepting layer 2. Then, the ink jet printing pattern 4 with the pigment ink is formed under a state not being infiltrated to the ink accepting layer 2, and can be easily erased when being rubbed with an eraser or a pencil eraser.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a pattern formed by ink-jet printing, a part of which can be erased by an eraser. If desired, a new pattern can be further written on the pattern. The present invention relates to a print sheet that can be printed.

[0002]

2. Description of the Related Art In recent years, with the spread of computer utilization technology, printing out data created by a computer using a printer has become popular. Printers used at that time include dot impact printers, laser printers, thermal printers, and ink jet printers.These are that there is almost no mechanical noise during printout, and the running cost associated with printout is low. Printers are widely used.

[0003] Normally, plain paper or coated paper is used as the paper for printing out by an ink jet printer. However, recently, paper made of a plastic film has been used because of its excellent water resistance and storage stability. Recording sheets provided with an ink receiving layer made of a hydrophilic polymer on the surface of a material are often used.

On the other hand, it is often necessary to erase a part of the print pattern of a recording sheet printed out by the ink jet printer and rewrite it, and some recording sheets have been proposed. (JP-A-8-207395).

[0005] However, in the case of printing out by using an ink jet printer using these recording sheets, the entire printed pattern is erased in the same manner by rubbing with an eraser or the like. In addition to the inconvenience of being erased, the pattern is fixed and cannot be erased after a long time.

[0006]

SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of the conventional erasable recording sheet, in which only a part of a print pattern printed by an ink jet printer is erasable and others are erased. The purpose of this erasable portion is to provide a new recording sheet that does not show a decrease in its erasing performance even after a long period of time.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to develop a recording sheet capable of selectively erasing only a part of a print pattern printed out by an ink jet printer. If you print out with an ink jet printer using two types of ink, a dye ink that can penetrate the ink receiving layer provided on the material film and a pigment ink that does not penetrate it, the part printed with the dye ink can not be erased, It has been found that the portion printed with the pigment ink is erasable, and that this erasing performance is maintained for a long time, and the present invention has been made based on this finding.

That is, the present invention has an ink receiving layer carrying an ink jet printing pattern of a dye ink on at least one side of a substrate film, and the surface of the ink receiving layer has compatibility with the ink receiving layer. An object of the present invention is to provide a partially erasable recording sheet that carries an ink jet print pattern made of a pigment ink having no ink.

In this recording sheet, the content ratio of the component (A) to the component (B) in the ink receiving layer is from 8: 2 to 6: 4 by weight, and the content of the component (C) is With respect to 100 parts by weight of the total weight of
Those in the range of 00 parts by weight, especially 40 to 80 parts by weight are preferred.

The component (A) is a cellulose-reactive crosslinking agent or polyvinyl alcohol crosslinked with urea,
The component (C) is advantageously a mixture of synthetic silica having an average particle size of 3.5 μm or less and synthetic silica having an average particle size of 6.0 μm or more. Further, on this recording sheet, a layer containing a dot shape adjusting agent can be laminated on the ink receiving layer.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The substrate film of the recording sheet of the present invention is not particularly limited, and can be arbitrarily selected from those conventionally used as the substrate of a recording sheet for an ink jet printer. . Such materials include, for example, polyethylene terephthalate,
Any one can be selected from polyethylene, polypropylene, polyamide and the like, and among them, polyethylene terephthalate is particularly preferable.
The thickness of the substrate film is usually in the range of 25 to 250 μm, preferably 50 to 100 μm. As this substrate film, a film which has been subjected to a mat treatment as required can be used.

In the recording sheet of the present invention, an ink receiving layer is provided on at least one side, that is, one side or both sides of the base film. In order to improve the adhesion between the ink receiving layer and the base film, If desired, an undercoat layer may be provided between the base film and the ink receiving layer. As the undercoat layer, a saturated polyester resin, a urethane resin, or the like is usually used, but a urethane resin is particularly preferable because of good adhesion to the ink receiving layer.
The thickness of the undercoat layer is usually in the range of 0.5 to 1.5 μm.

Next, as the ink receiving layer, for example, a layer mainly composed of (A) crosslinked polyvinyl alcohol, (B) polyvinylpyrrolidone and (C) synthetic silica is used. The polyvinyl alcohol used as the component (A) usually has a degree of polymerization of 1,000 or more, and particularly 1
Those having a range of 000 to 3000 are preferred. When the degree of polymerization is less than 1,000, the ink drying property (ink absorption property) and the water resistance of the film become insufficient. The polyvinyl alcohol is preferably a partially saponified or completely saponified polyvinyl acetate having a saponification degree of 75 mol% or more, particularly preferably a partially saponified compound having a saponification degree of 75 to 90 mol%. When the degree of saponification is less than 75 mol%, the ink absorption speed becomes low.

The component (A) may be cross-linked with a cellulose-reactive cross-linking agent or urea. The cellulose-reactive cross-linking agent is a cross-linking agent having reactivity to hydroxyl groups of cellulose, such as dimethylol ethylene urea, dimethylol propylene urea, dimethylol alkyl triazone, Examples thereof include cyclic or heterocyclic urea derivatives such as methylated dimethyloluron and dimethylolglyoxal monourein. These react with the functional groups in the polyvinyl alcohol in the presence of a catalyst such as ammonium chloride, ammonium nitrate, ammonium sulfate or the like to form a three-dimensional structure.
The cellulose-reactive crosslinking agent or urea is used in an amount of usually 4 to 12 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of polyvinyl alcohol. If the amount is less than 4 parts by weight, sufficient improvement in water resistance cannot be obtained, and if it exceeds 12 parts by weight, the ink absorbency tends to decrease. Further, the catalyst used in combination therewith is preferably used in a proportion of usually 20 to 100% by weight with respect to the fibrin-reaction type crosslinking agent.

Next, the polyvinyl pyrrolidone used as the component (B) preferably has a molecular weight of usually 40,000 or more, particularly preferably in the range of 600,000 to 28,000,000. If the molecular weight is less than 40,000, the ink absorption rate and the acceptability are low, and as a result, the drying property of the ink is reduced. The synthetic silica used as the component (C) includes an oil absorption of 75 to 105 ml and a specific surface area of 500 to 900.
Those having m ² / g are preferred. If the oil absorption is less than 75 ml or the specific surface area is less than 500 m ² / g, the dye ink sufficiently penetrates and becomes difficult to absorb during ink-jet printing with the dye ink, and the oil absorption is 105 ml.
If it is larger than this, or if the specific surface area is larger than 900 m ² / g, as a result of penetrating the pigment ink, the pattern printed with the pigment ink becomes difficult to be erased by an eraser or the like.

The synthetic silica has an average particle size of 0.1.
Those having a range of 5 to 15 μm, preferably 0.8 to 9 μm are suitable. When the average particle diameter is less than 0.5 μm, the ink drying property is poor. When the average particle diameter is more than 15 μm, the dot shape does not easily become a perfect circle, and the image resolution tends to decrease.

Particularly preferred as the synthetic silica of the component (C) is a mixture of a synthetic silica having an average particle size of 3.5 μm or less and a synthetic silica having an average particle size of 6.0 μm or more. The mixing ratio between the small and large average particle diameters is preferably in the range of 8: 2 to 2: 8 by weight.

The content ratio of the component (A) and the component (B) is preferably in the range of 8: 2 to 6: 4 by weight. If the proportion of the component (A) is less than this, the water resistance will decrease, causing stickiness, and if the proportion of the component (A) is greater than this, the absorbability of the dye ink will decrease.

Next, the content of the component (C) is 30 to 30 parts by weight based on 100 parts by weight of the total weight of the components (A) and (B).
It is selected in the range of 100 parts by weight, preferably 40 to 80 parts by weight. When the amount is less than 30 parts by weight, the absorbability of the dye ink is reduced, and when it exceeds 100 parts by weight, the water resistance is reduced.

The recording sheet of the present invention can be produced, for example, as follows. That is, first, the component (A), the component (B) and the component (C) are dissolved or dispersed in an aqueous medium at a predetermined ratio, respectively, to obtain a solid content of 10 to 1%.
After preparing a coating liquid of about 5% by weight, an ink receiving layer is provided by coating and drying on a base film or an undercoat layer provided as required according to a conventional method. At this time, conventionally used various additives such as a surfactant, a lubricant, a stabilizer, and a coloring agent can be added to the coating liquid. The thickness of the ink receiving layer is usually 5 to
It is in the range of 30 μm, preferably 10 to 20 μm.

In the present invention, a dot shape adjusting agent-containing layer can be provided on the ink receiving layer thus provided, if desired. As the dot shape adjusting agent, for example, a quaternary ammonium salt type acrylic resin is preferable. Specific examples of the quaternary ammonium salt type acrylic resin include a copolymer salt of an alkyl acrylate or an alkyl methacrylate with a dialkylamino acrylate or a dialkylaminoalkyl methacrylate. Such quaternary ammonium salt type acrylic resins are known, for example, a molar ratio of butyl methacrylate to dimethylaminoethyl methacrylate of 1:
The quaternary salt of the copolymer (1) is commercially available.

In order to form the dot shape adjusting agent-containing layer, the dot shape adjusting agent was dissolved in a suitable solvent, for example, alcohol or a mixture of alcohol and water, and the solution was applied on the ink receiving layer. Then, it may be dried. At this time, the dot shape adjusting agent may be formed on the ink receiving layer, or may be partially dissolved or impregnated in the ink receiving layer.

The coating amount of the dot shape adjusting agent is 3 to 10
The range of g / m ² is appropriate. It coating amount of the dot shape modifier sharpness of the image (image resolution) is insufficient at less than 3 g / m ^2, greater than 10 g / m ² when the ink absorbency and ink drying property is lowered. This layer has the effect of forming the dot shape to be a more perfect circle and further preventing ink bleeding.

In the present invention, when the ink receiving layer and the dot shape adjusting agent-containing layer are provided on one side of the base film, the mat layer may be provided on the back surface of the base film, that is, on the side opposite to the ink receiving layer. Alternatively, an ink receiving layer can be provided. The mat layer is formed of a binder and a matting agent.Examples of the binder include a thermoplastic resin, a thermosetting resin, a photocurable resin, and the like.Specifically, acrylic, urethane, polyester, Examples of each resin include vinyl chloride resins. As the matting agent, for example, silica, zirconia, clay, kaolin, alumina, titania, zeolite, calcium carbonate, barium sulfate, magnesium hydroxide, calcium phosphate, inorganic powders such as glass, acrylic resin, urethane resin, Vinyl chloride resin, benzoguanamine resin,
Synthetic resin powders such as benzoguanamine / melamine / formaldehyde condensate are exemplified. The average particle size of the matting agent is 0.1 to 20 μm, preferably 2 to 10 μm.
Is preferable. Further, when the ink receiving layer is also formed on the back surface of the base film, the same one provided on the front surface of the base film may be provided, or the other, for example, does not contain a matting agent, Alternatively, a transparent ink receiving layer containing a very small amount may be provided.

The thickness of the mat layer is advantageously in the range of 1 to 10 μm, preferably 3 to 7 μm, from the viewpoint that curl prevention and good writability are obtained. Further, the mat layer may contain those conventionally used as additives, for example, a surfactant, a lubricant, a stabilizer, and a colorant.

The recording sheet of the present invention has two types of printing patterns that are ink-jet printed on the printing sheet having the above configuration. One of them is an ink jet printing pattern formed by the dye ink penetrating into the ink receiving layer, and the other is a surface of the ink receiving layer or a dot shape adjusting agent-containing layer optionally laminated thereon. 4 is an ink jet printing pattern formed by the pigment ink carried on the substrate.

The dye ink is not particularly limited, and may be arbitrarily selected from those used in ordinary ink jet printing. As such a dye, for example, a dye such as malachite green, rhodamine B or G, victoria blue B, permanent green, permanent rhodamine, or permanent blue can be used in a vehicle such as mineral oil, vegetable oil, tung oil, synthetic drying oil, or alkyd resin oil. Some are dissolved.

The pigment ink is not particularly limited and may be arbitrarily selected from those usually used for ink jet printing. Such materials include, for example, synthetic inorganic pigments, azo pigments,
There are pigments such as lake pigments and phthalocyanine pigments dispersed in vehicles such as water, aqueous solutions containing surfactants and dispersants, and solvents. This pigment has a particle size of 0.5 to
Those having a thickness of 2 μm, preferably about 1 μm are used.

Among these ink jet printing patterns, those formed by dye ink are those which penetrate into the ink receiving layer and are fixed, that is, patterns which are not erased by friction with an eraser or the like. The formed pattern is a pattern that does not penetrate into the ink receiving layer, is merely carried on the ink receiving layer, and is erased by friction with an eraser or the like. The pattern formed by the pigment ink can be erased for a long time, and can be easily erased even after being left for 30 days, for example.

FIG. 1 is a longitudinal sectional view of a model showing the basic structure of the recording sheet of the present invention. An ink receiving layer 2 having a predetermined composition is provided on one surface of a base film 1, and an ink jet ink using dye ink is provided. A print pattern 3 is formed in a state of penetrating the ink receiving layer 2, and an ink jet print pattern 4 made of pigment ink is carried on the surface of the ink receiving layer 2. Since the ink-jet print pattern 4 made of the pigment ink is formed without penetrating the ink receiving layer, it can be easily erased by rubbing with an eraser or a pencil-type eraser.

[0031]

Next, the present invention will be described in more detail with reference to examples.

Example 1 6 parts by weight of polyvinylpyrrolidone (molecular weight: 1280000), 14 parts by weight of polyvinyl alcohol (polymerization degree: 2,000, saponification degree: 88.0 mol%), synthetic silica powder having an average particle diameter of 3.5 μm (specific surface area: 700 m ²⁾ / G) 6 parts by weight, 1.4 parts by weight of dimethylol glyoxal monourein, which is a cellulose-reactive crosslinking agent, 0.3 parts by weight of ammonium chloride, 40 parts by weight of ethanol, 20 parts by weight of propylene glycol monomethyl ether and 108 parts of water Then, 0.3 parts by weight were mixed to prepare a coating liquid for forming an ink receiving layer.

On one side of a polyethylene terephthalate film having a thickness of 50 μm, a urethane resin having a thickness of 1.0
After the undercoat layer having a thickness of μm was provided, the coating solution was applied onto the undercoat layer using a wire bar, and heated at 130 ° C. for 5 minutes to form an ink receiving layer having a thickness of about 15 μm.

Next, Hewlett-Packard (Hew
Using an inkjet plotter (Design Jet 750C) manufactured by Lett Packard, Inc., a dye ink (manufactured by Hewlett Packard, trade name “5”)
1644C "), the basic structure of the building design is inkjet printed on the ink receiving layer,
Further, the attached structure was ink-jet printed using a pigment ink (Hewlett Packard, trade name "51645A").

After leaving for 1 hour, the printed pattern was rubbed with an eraser, and the attached structure was completely erased.
The basic structure was not damaged at all. After leaving for 2 months, the same operation was performed, but there was almost no change in the erasing performance of the inkjet print pattern using the pigment ink. For comparison, a commercially available inkjet recording paper was subjected to an erasure test on the same pattern that was inkjet-printed with the pigment ink described above. As a result, the erasure was possible after one hour, but was completely eliminated after two months. Not erased.

Example 2 6 parts by weight of polyvinylpyrrolidone (molecular weight: 1280000), 14 parts by weight of polyvinyl alcohol (degree of polymerization: 2,000, saponification degree: 88.0 mol%), synthetic silica powder having an average particle size of 3.5 μm (specific surface area: 700 m ²⁾ / G) 6 parts by weight, 4 parts by weight of calcium carbonate powder having an average particle size of 2.0 μm, 1.4 parts by weight of dimethylol glyoxal monourein which is a cellulose-reactive crosslinking agent, 0.3 parts by weight of ammonium chloride, ethanol 40 parts by weight, 20 parts by weight of propylene glycol monomethyl ether and 108.3 parts by weight of water were mixed to prepare a coating liquid for forming an ink receiving layer.

A polyethylene terephthalate film having a thickness of 50 μm was coated on one surface with a urethane resin having a thickness of 1.0 μm.
After the undercoat layer having a thickness of μm was provided, the coating solution was applied onto the undercoat layer using a wire bar, and heated at 130 ° C. for 5 minutes to form an ink receiving layer having a thickness of about 15 μm.

Further, a quaternary ammonium salt type acrylic resin [Saftomer CP-2000, manufactured by Mitsubishi Yuka Co., Ltd.]
1.0 part by weight, 10.0 parts by weight of ethanol and 89.0 parts of water
A part of the dot shape adjusting agent-containing layer forming liquid is prepared, applied to the ink receiving layer, and dried to form a dot shape adjusting agent-containing layer containing 4 g / m ² of the dot shape adjusting agent. Formed.

Next, on the back surface of the ink receiving layer, 20 parts by weight of a binder (acrylic copolymer resin), 10 parts by weight of a matting agent (synthetic silica powder, average particle size of 3.5 μm) and water 7
0 parts by weight of a mat layer forming coating solution,
By heating at 2 ° C. for 2 minutes, a mat layer having a thickness of 5 μm was formed.

With respect to the recording sheet thus obtained, a print pattern was formed using a dye ink and a pigment ink in the same manner as in Example 1, and an erasure test was performed with an eraser. The results were the same as those in Example 1. was gotten.

Examples 3 and 4 A recording film was produced in the same manner as in Example 2 except that the composition having the composition shown in Table 1 was used as the ink receiving layer forming coating liquid. When a print pattern was formed using a dye ink and a pigment ink in the same manner as in Example 2, and an erasure test was performed using an eraser, completely the same results were obtained.

Comparative Examples 1 and 2 A recording film was produced in exactly the same manner as in Example 2 except that the composition shown in Table 1 was used as the ink receiving layer forming coating liquid. When a print pattern was formed using a dye ink and a pigment ink in the same manner as in Example 2, and an erasure test was performed using an eraser, the pigment ink could not be erased.

[0043]

[Table 1] (Note) 1) Synthetic silica powder: particle size 3.5 μm, oil absorption 95 m
1, specific surface area 700 m ² / g 2) synthetic silica powder: particle size 3.5 μm, oil absorption 210 m
1, specific surface area 300m ² / g

[0044]

The recording sheet of the present invention can be erased as needed by ink-jet printing a pattern which does not need to be erased with a dye ink and a pattern which needs to be erased with a pigment ink as needed. There is an advantage that the pattern can be corrected by the above method.
In addition, there is an advantage that the erasing performance of the print pattern portion by the pigment ink does not decrease over a long period of time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a recording sheet model of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base film 2 ink receiving layer 3 inkjet printing pattern using dye ink 4 inkjet printing pattern using pigment ink

Claims (6)

[Claims] 1. A pigment ink having an ink receiving layer carrying an ink-jet printing pattern of a dye ink on at least one side of a base film, and having no ink receiving layer compatibility on the surface of the ink receiving layer. A partially erasable recording sheet carrying an ink jet print pattern according to claim 1. 2. An ink receiving layer comprising (A) a crosslinked polyvinyl alcohol, (B) polyvinylpyrrolidone, (C) an oil absorption of 75 to 105 ml, and a specific surface area of 500 to
^2. The recording sheet according to claim 1, comprising 900 m ² / g of synthetic silica. 3. The ink receiving layer according to claim 1, wherein the content ratio of the component (A) to the component (B) is 8: 2 to 6: 4 by weight, and the content of the component (C) is between (A) and (B). 3. The recording sheet according to claim 2, wherein the amount of the recording sheet is 30 to 100 parts by weight based on 100 parts by weight in total with the component (B). 4. The recording sheet according to claim 2, wherein the component (A) is a fibrin-reaction type crosslinking agent or a polyvinyl alcohol crosslinked with urea. 5. The recording sheet according to claim 2, wherein component (C) is a mixture of synthetic silica having an average particle diameter of 3.5 μm or less and synthetic silica having an average particle diameter of 6.0 μm or more. 6. The recording sheet according to claim 1, wherein a dot shape adjusting agent-containing layer is further laminated on the ink receiving layer.